Deckard is “chicken”, he is reluctant to take the job.
Deckard may be getting *too* involved (probably meant in respect to Rachael).
a) “Gaff was here!” basically, it was a calling card;
b) In the DC, there is an extra layer to it: (See question “Is Deckard a Replicant”)
Posted in: 4.9. Miscellaneous Movie Questions